Question: Solve for $x$ and $y$ using substitution. ${x+y = -1}$ ${x = -6y+4}$
Since $x$ has already been solved for, substitute $-6y+4$ for $x$ in the first equation. ${(-6y+4)}{+ y = -1}$ Simplify and solve for $y$ $-6y+4 + y = -1$ $-5y+4 = -1$ $-5y+4{-4} = -1{-4}$ $-5y = -5$ $\dfrac{-5y}{{-5}} = \dfrac{-5}{{-5}}$ ${y = 1}$ Now that you know ${y = 1}$ , plug it back into $\thinspace {x = -6y+4}\thinspace$ to find $x$ ${x = -6}{(1)}{ + 4}$ $x = -6 + 4$ ${x = -2}$ You can also plug ${y = 1}$ into $\thinspace {x+y = -1}\thinspace$ and get the same answer for $x$ : ${x + }{(1)}{= -1}$ ${x = -2}$